3, 5-diketo pyrazolidine color formers



Patented Sept. 23, 1947 3,5-DIKETOTYRAZOEIDINEGOIJOR LFORMERS John David "Kendall and Douglas James Fry, 'Ilford, "England, assignorsto IlfordLimited, "'Ilford,'England, a British company No Drawing. Application Mayi3, l945ys'ei ial No. 591,830. In Great Britain-May 12,;1944

8 Claims.

1 "This invention relates to colour photography and particularly to dyestulf intermediates for use in 'colourphotographic processes.

Processes of colour phdtography are'wellknown inwhich coloured images are produced'by the development of "reducible silver salt images by means of aromatic primary amino developing agents in "the presence of compounds, generally known as colour-formers or colour-couplers,

which couple with the-oxidation products of such developers, formed during development, to form quinone-imine or azomethine dyes. The colourcouplers may be present in the developing solution employed, or may be included in a photographic emulsion layer which contains the reduciblesilver salt image, or in an adjacent layer or a layer separated from the said emulsion layer only by a thin water-permeable layer. Thedeveloping agent may be, for-example, p-phenylene diamineor its N.N-dialkyl derivatives, e.:g. NN- dimethyl or N .Ndiethyl-p-phen-ylene diamines, or 'homologues thereof, e. g. '5-diethylamino-2- amino-toluene.

Large numbers of colour-couplers have been described in the extensive literature dealing with this type of colour photographic process. The requirements for a satisfactory colour-coupler, however, are rather strict. Thus, it must be capable of ready incorporation into the developing bath or photographic layer into which it is desired to include it, and where it is included .in a photographic layer, neither it nor the dye derived from it must have any substantial tendency to diffuse from such layer, either into adj acent layers of the photographic element, or into processing baths. Moreover, it must be selected so that the colour of the dye obtained from it is suitable for the particular colour process with which it is intended to be used.

According to the present invention a process of colour photography comprises developing a reducible silver salt image by means of an aromatic primary amino developing agent in the presence of a compound of the general formula:

where R1 and R2 are hydrogen atoms or substituted or unsubstituted hydrocarbon groups, e. g. alkyl, aralkyl or and groups, or heterocyclic groups, e. g. methyl, ethyl or higher alkyl, benzyl, phenyl or naphthyl groups which may be substituted by alkyl, aryl, aralkyl, amino, substituted amino, nitro, hydroXy, alkoxy, oxyalkyl, sulphonic and *carboxylic groups or I halogen atoms.

or .quinolyl, .pyridy1,furyl and similar heterocyclic groups.

These compounds may be prepared by anyconvenient'method. Thus, fortexample, '1:2'-diphenyl-3.5-diketo pyrazolidine may be prepared from hydrazobenzene, diethyl 'malonate or other dialkyl malonate and-sodium ethoxide in the manner described in Berichte der DeutscheniCheinischen Gesellschaft, volume 73B, pages 8204322, and other compounds can be prepared analogously by varying the nature of the starting materials. Thus, using p.p-dichloro-hydrazobenzene the corresponding 1.2-di-(p-chlor phenyl) -3.5-diketo-pyrazolidine (melting point 177 'C.) may be obtained. Similarly there may be employed: 4.4' dimeth'oxy hydrazobenzene, '3Z3'-dinitro-hydrazobenzene, dixenyl hydrazine, ditolyl hydrazine, B18-dinaphthyl hydrazine,'2.2'-1epidyl hydrazineand 2.2-quinoly1 hydrazine.

Particular compounds which may be 'used in.

accordancewith the present invention are:

1 -phenyl-3.5-diketo pyrazolidine -1-methyl- 3.5-diketopyrazolidine 1.2-di(4'-Inethoxyphenyl) -3.5-diketo pyrazolidine:

1.2-di(3-nitrophenyl) -3.5-diketo pyrazolidine 1 .2-dixeny1-3 .S-diketo pyrazolidine 1.2-diquinolyl-3.5-diketo pyrazolidine 1.2-ditolyl-3.5-diketo pyrazolidine These compounds are made by t-he' proce's's 'described above using the appropriate reagents.

The colour-couplersof this invention yield acct: magenta images suitable for use in three-colour subtractive colour processes.

The colour-"couplers of this invention may b included in a developing solution containing an aromatic primary amino developingagenu-or may be included in a silver halide emulsion layer, or in a water-permeable colloid layer coated next to a silver halide emulsion layer, or separated therefrom only by a thin water-permeable colloid layer. Thus, for example, the colour-couplers of this invention may be used in any of the colour processes of U. S. Patents Nos. 2,350,380, 2,363,764 and 2,369,171 and British Patents Nos. 551,116, 551,117, 554,302 and 556,858.

The formation of coloured images by means of the colour-couplers of this invention may be applied to the development of a reducible silver salt image which is an original latent image formed in the emulsion layer by exposure to light or which is an image obtained by the conversion of a silver image to a reducible silver salt image,

by the usual bleachingtechnique.

Although this invention is primarily concerned with colour photographic processes in which the dye is formed by the coupling of the colour-couplers of the invention with the oxidation products of an aromatic primary amino developing agent formed in situ during the development of a reducible silver salt image, the colour-couplers of the invention may also be employed in other colour photographic processes, e. g. process in which the dye is formed by direct coupling between the colour-coupler and a nitroso aniline, e. g. p-nitroso dialkyl aniline, or between the colour-coupler and a diazo compound. As an example of this latter type of process a colourcoupler may be present in a layer containing a reducible silver salt image, such image, developed with an aromatic primary amino developing:

agent forming an azomethine dye image in situ with the developed silver image, the residual colour-coupler coupled with a diazo compound applied in solution to the photographic element, and the original azomethine dye image bleached out, leaving only the azo dye image in the layer.

What we claim is:

1. A process of colour photography which comprises developing a reducible silver salt image in a photographic element by means of an aromatic primary amino developing agent in the presence of a compound of the general formula:

CO CO where each of R1 and R2 is a group selected from the class consisting of hydrogen atoms, hydrocarbon groups, amino-, nitro-, hydroxy-, alkoxy-, oxyalkyl-, su1fonic-, carboXylic-, and halogensubstituted hydrocarbon groups and heterocyclic groups.

2. A process of colour photography which comprises developing a reducible silver salt in a photographic element by means of a solution of an aromatic primary amino developing agent containing a compound of the general formula:

where each of R1 and R2 is a group selected from the class consisting of hydrogen atoms, hydrocarbon groups, amino-, nitro-, hydroxy-, alkoxy-, oxyalkyl-, sulfonic-, carboxylic-, and halogensubstituted hydrocarbon groups and heterocyclic groups.

3. A photographic element for colour photography which comprises a support hearing at least one layer of a light-sensitive silver halide emulsion containing a compound of the general formula:

where each of R1 and R2 is a group selected from the class consisting of hydrogen atoms, hydrocarbon groups, amino-, nitro-, hydroxy-, alkoxy-, oxyalkyl-, sulfonic-, carboxylic-, and halogensubstituted hydrocarbon groups and heterocyclic groups,

5. A process of colour photography which comprises forming a reducible silver salt image in an emulsion layer of a photographic element which contains a compound of the general formula:

where each of R1 and R2 is a group selected from the class consisting of hydrogen atoms, hydrocarbon groups, amin0-, nitro-, hydroxy-, alkoxy-, oxyalky1-, sulfonic-, carboxylic-, and halogensubstituted hydrocarbon groups and heterocyclic groups, and developing said image with an aromatic primary amino developing agent.

6. A process of colour photography which comprises forming a reducible silver salt image in an emulsion layer of a photographic element which contains a compound of the general formula:

R1N---NR2 to C0 Ci where each of R1 and R2 is a group selected from the class consisting of hydrogen atoms, hydrocarbon groups, amino-, nitro-, hydroxy-, alkoxy-, oxyalkyl-, sulfonic-, carboxylic-, and halogensubstituted hydrocarbon groups and heterocyclic groups, and developing said image with an N,N- dialkyl-p-phenylene diamine.

7. A process of colour photography which comprises forming a reducible silver salt image in an emulsion layer of a photographic element which includes, adjacent thereto, a layer containing a compound of the general formula:

where each of R1 and R2 is a group selected from the class consisting of hydrogen atoms, hydrocarbon groups, amino-, nitro-, hydroxy-, alkoxy-, oxya1kyl-, sulfonic-, carboxylic-, and halogensubstituted hydrocarbon groups and heterocyclic groups, and developing said image with an aromatic primary amino developing agent.

8. A process of colour photography which comprises forming a reducible silver salt; image in an emulsion layer of a photographic element which includes, adjacent thereto, a layer containing a compound of the general formula:

where each of R1 and R2 is a group selected from the class consisting of hydrogen atoms, hydrocarbon groups, amino-, nitro-, hydroxy-, alkoXy-, oxyalkyl-, sulfonic-, carboxylic-, and halogensubstituted hydrocarbon groups and heterocyclic groups, and developing said image with an N,N- dialkyl-p-phenylene diamine.

JOHN DAVID KENDALL.

DOUGLAS JAMES FRY. 

